Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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248 FXUS65 KBOU 050935 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 335 AM MDT Wed Jun 5 2024 .KEY MESSAGES... - Summer heat through the rest of this week, with a few 90 degree readings over the plains, with today and Friday the hottest days. - Increasing chances for showers and thunderstorms this weekend into early next week, along with slightly cooler temperatures. && .SHORT TERM /Through tonight/... Issued at 335 AM MDT Wed Jun 5 2024 For today, the forecast area will be under increasing influence of a large and hot dome of high pressure over the Southwest U.S. Mid level temperatures will show significant warm advection, with 700 mb temperatures rising 5C from yesterday. Given full sunshine and still some downslope winds, that spells high temperatures in across almost all of the plains and I-25 Corridor reaching the lower 90s for the first time this year. For tonight, a weak backdoor cool front arrives late this evening. That front is dry with a continuation of mostly clear skies. The lighter winds behind the front will allow for stronger low level inversions, and cooler temperatures to spread back to the foothills (versus this morning`s downslope induced warm temperatures in the 60s in some spots). && .LONG TERM /Thursday through Tuesday/... Issued at 335 AM MDT Wed Jun 5 2024 There is good agreement on upper level ridging generally dominating the upper level pattern for the extended period. Thursday will be a degree or two cooler than Wednesday with the passage of a backdoor cold front. Easterly component flow settles in across the plains for much of the day. Temperatures will still likely be above normal across the I-25 corridor and plains with highs in the mid to upper 80s. Conditions will be mainly dry. There is some very marginal moisture/instability for the higher elevations south of I-70, so kept in low chances (< 20%)for a few showers/storms in the afternoon. By Friday, the upper ridge shifts further east over Colorado accompanied by a mid-level thermal ridge. Warming 700mb temperatures and downslope flow will support a good chance for highs in the upper 80s to low 90s for plains/urban corridor. Ensembles show a signal for anomalous moisture advecting into the region Friday through the weekend. Ensemble guidance shows mean precipitable water values 130-175% of normal. Within this timeframe, a few weak shortwave troughs move through the northwesterly flow aloft bringing periods of weak synoptic ascent. Slight cooling aloft will help bring more instability to promote showers and thunderstorms. Details still remain fuzzy on the timing and progression/track of the shortwave troughs with notable differences among deterministic guidance. Overall, the weekend into early next week looks slightly cooler with scattered/likely showers and thunderstorms. By mid-week next week, the upper pattern favors a warming and drying trend as another ridge builds in from the west. && .AVIATION /06Z TAFS through 06Z Thursday/... Issued at 1132 PM MDT Tue Jun 4 2024 VFR through Wednesday night with mostly clear skies. Winds are transitioning to more of a south/southwest component and will stay that way through Wednesday morning. There could be a few puffs of light westerly wind til about 08Z, and then a possible tilt toward SSE winds 11Z-15Z, but overall wind speeds will be light. Sunshine and mixing will aid winds turning to the west/northwest toward 18Z with gusts 18-24 kts during the afternoon. Expect a backdoor weak cold front to arrive with a shift to northeast winds 10-12 kts toward 05Z Thursday, or the end of this TAF period. && .HYDROLOGY... Issued at 335 AM MDT Wed Jun 5 2024 Mountain snowmelt and runoff is accelerating with warmer temperatures, and high country streams will continue to see increasing flows through the end of the week. Hydrologic forecasts continue to show elevated flows, with a few sites along the Colorado and Fraser Rivers in Grand County reaching Action Stage by Friday. Action Stage means flows will be high and fast with near bankfull levels, but so far the threat of any flooding appears limited. Many other streams, including those along the Front Range, are seeing quick rises as well given the very warm temperatures. Use caution along these streams, and respect the fast moving and cold flows. Meanwhile, the threat of burn area flash flooding will gradually increase this weekend into early next week as a moist airmass advects into the region. Confidence is low for any given day, but something worth watching as we get closer to the weekend. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Barjenbruch LONG TERM...Mensch AVIATION...Barjenbruch HYDROLOGY...Barjenbruch/Mensch